An atom probe (e.g., atom probe microscope) is a device which allows specimens to be analyzed on an atomic level. For example, a typical atom probe includes a specimen mount, an electrode, and a detector. During analysis, a specimen is carried by the specimen mount and a positive electrical charge (e.g., a baseline voltage) is applied to the specimen. The detector is spaced apart from the specimen and is negatively charged. The electrode is located between the specimen and the detector, and is either grounded or negatively charged. A positive electrical pulse (above the baseline voltage) and/or a laser pulse (e.g., photonic energy) are intermittently applied to the specimen. Alternately, a negative pulse can be applied to the electrode. Occasionally (e.g., one time in 100 pulses) a single atom is ionized near the tip of the specimen.
The ionized atom(s) separate or “evaporate” from the surface, pass though an aperture in the electrode, and impact the surface of the detector. The identity of an ionized atom can be determined by measuring its time of flight between the surface of the specimen and the detector, which varies based on the mass-to-charge ratio of the ionized atom. The location of the ionized atom on the surface of the specimen can be determined by measuring the location of the atom's impact on the detector. Accordingly, as the specimen is evaporated, a three-dimensional map of the specimen's constituents can be constructed.
Generally, when it is desired to analyze a piece of bulk material in an atom probe a portion of the material must be removed from the piece of bulk material and shaped into a needle shape with a sharp tip (e.g., a tip radius of 100 nanometers) or a micotip array. These conventional atom probe specimens are suitable for the very high concentrated electrical fields associated with evaporating ionized atom(s) from the specimen. These needle shaped specimens typically have a length of 100 microns or greater. The process of forming these needle shaped specimens can be a labor intensive process and can take a significant amount of time. Once a specimen is formed, the specimen is generally placed in the atom probe and analyzed.